1. Field of Invention
This invention relates to security devices and is particularly directed to through-door viewing devices for permitting a person inside a house, apartment or the like to observe persons or things outside the door without the necessity of opening the door.
2. Prior Art
In recent years, crimes such as burglary, mugging, rape and even murder have become increasingly common. Many people have installed multiple locks and dead bolts on their doors to prevent break-ins. Unfortunately, criminals have responded to this by employing numerous subterfuges, such as claiming to be delivery men, telegraph boys or the like, to persuade a potential victim to open their door and, hence, to allow the criminal to circumvent the locks and dead bolts. Accordingly, several prior art devices have been proposed to enable a person to see the area outside the door without the necessity of opening the door. A search in the U.S. Patent Office has revealed the following patents:
______________________________________ U.S. Pat. No. INVENTOR ISSUE DATE ______________________________________ 2,489,060 F. G. Tappe Nov. 22, 1949 2,491,758 A. Nichols et al Dec. 20, 1949 2,638,810 G. R. Berleme May 19, 1953 4,561,116 G. Neyret Dec. 24, 1985 ______________________________________
Each of these references relates to through-door viewing devices. However, none of the prior art devices provides significant peripheral vision for the viewer. Thus, if the person seeking entrance is not standing directly in front of the door, the potential victim cannot see them and may proceed to open the door. So-called "fish eye" or wide angle lenses have been employed in some through-door viewing devices to attempt to solve this problem. However, these lenses produce considerable distortion, especially in areas approaching 90.degree. to the viewing axis, and, hence, provide little, if any, help in observing and identifying a person seeking entrance. Thus, none of the prior art through-door viewing devices have been entirely satisfactory.